Human papillomavirus 16 E7 protein inhibits interferon‐γ‐mediated enhancement of keratinocyte antigen processing and T‐cell lysis

Infection of epithelium with human papillomavirus (HPV) 16 is generally prolonged, suggesting an ineffective virus-specific immune response, and prolonged infection promotes anogenital cancer. To determine whether poor antigen presentation by HPV-infected keratinocytes (KCs) contributes to prolonged HPV infection, KCs and KCs expressing HPV 16 E7 protein (E7-KCs) were compared for susceptibility to T-cell-mediated lysis directed to ovalbumin (OVA) processed for presentation by the KCs. Interferon (IFN)-γ efficiently enhanced susceptibility to lysis of KCs presenting OVA, but not of E7-KCs similarly presenting OVA. E7-KCs also exhibited impaired IFN-γ-induced upregulation of transcription of major histocompatibility complex class I antigen processing and presentation-associated genes, and of membrane SIINFEKL-H-2K(b) complexes. Thus, expression of HPV 16 E7 protein in KCs may inhibit enhancement by IFN-γ of KC sensitivity to T-cell lysis, by impairing antigen presentation.